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(forget I said that)

Yesterday there was a Guardian article about the philosopher (and sculptor, and jazz pianist, and sailor, and cidermaker . . .) Dan Dennett, who it turns out is a man too talented to be allowed to live. I have recommended his work to some of you before - especially Consciousness Explained and Darwin's dangerous Idea.

I'm afraid that Penrose's view is much closer to my own than Dennett or Hofstadter (though I think the latter two are better writers). Penrose was widely (and unfairly I thought) criticised for providing arguments in principle not proofs. Fundamentally I have much sympathy with his main thrust, that nothing we currently know about in physics can genuinely explain consciousness.

His argument is more that current physics forbids consciousness, therefore the only major hole in it - gravity - must therefore take a particular form, and consciousness must depend on gravity. The fact that this all follows from a reading of Gödel that pretty much everyone else thinks is hilariously wrong doesn't exactly promote the view to me, regardless of his excellence in other areas.

Yes, or better phrased, that nothing in current physics can explain consciousness. To me this is self-evident. I would have willingly accepted that as an axiom.

therefore the only major hole in it - gravity - must therefore take a particular form

I wish my copy of emperor wasn't in my office (and my copy of shadows is missing presumed lent)... that is certainly not what I took away from it. Certainly he wished to argue for a certain form of those physical laws - he's something of an expert there. But again, I recall this differently - that that was an optional part of his argument about minds... "Having done all that, I wish to convince you of that the following is one possible way forward..." I would say that his argument did not in the slightest rely on any particular form of theories on gravitation.... he just wished to champion one.

The fact that this all follows from a reading of Gödel that pretty much everyone else thinks is hilariously wrong

That was part of what I meant about the condemnation. I wouldn't say his reading of it was hilariously wrong but I would agree it is wrong. But his position was not that everything followed from that... his position remained tenable without that part of the argument and that is how I took his position. I did not believe his argument via Goedel was correct but having removed it totally the rest of his position was still intellectually sufficiently coherent for me.

[What is interesting, is that while everyone agrees that his interpretation of Godel is wrong there's a considerable amount of disagreement about WHY it is wrong -- which is in itself intriguing. If the experts in a field are all totally in agreement that someone is wrong in mutually contradictory ways then that at least tells you things aren't as simple as they might appear.]

1: Because of the arguments of Lucas and Searle, we know that consciousness cannot be implemented on a Turing machine.2: But everything we know how to build using the laws of modern physics can be implemented on a Turing machine.3: So there must be a super-Turing bit of physics hiding in Nature that we don't know about.4: Where's a big unknown place to put it? How about Quantum Gravity?5: How the hell can QGT act on the brain? Through, er, weird tubule thingys?

His presentation of Lucas's argument is superb and the most compelling I've ever known. I don't have a good knock-down reply; the best counter-argument is the seemingly insurmoutable problems you encounter when you try and bridge over what seem at first to be petty, trivial problems with it.

His falling for Searle's emotionally-laden nonsense, on the other hand, is just embarrassing in one so bright.